Description

We using log error notification service: SQL Server Agent -> Alerts
Correspondingly logging errors (RAISERROR WITH LOG;) sends message by e-mail to admins
If anywhere, any provider with external context run fails on initialization, then alert system will fall off. And only system/service restart restores it.
At the same time other mechanisms, such as providers, e-mail etc. continues normal function (though some of them doesn't immediately, it depends)
Links for settings instructions:
http://support.microsoft.com/kb/2647989
http://msdn.microsoft.com/en-us/library/ms186358.aspx
http://msdn.microsoft.com/en-us/library/ms189982(v=sql.100).aspx
The use of an external context run is necessary due to problem providers with memory leaks and crashes (Oracle provider for example)